Re: [PATCH v2] powerpc/config: powernv_defconfig updates

[Balbir Singh <bsingharora@gmail.com>]

On Wed, Apr 11, 2018 at 8:42 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
> On Wed, 11 Apr 2018 20:04:45 +1000
> Balbir Singh <bsingharora@gmail.com> wrote:
>
>> On Wed, Apr 11, 2018 at 7:12 PM, Nicholas Piggin <npiggin@gmail.com> wrote:
>> > For consideration:
>> >
>> > * Add IPv6 support built in + additional modules - Because it's 2018 maan.
>> > * Add DEFERRED_STRUCT_PAGE_INIT - Let's see what breaks.
>>
>> We did not find any benefits with this on a P8 in terms of boot time
>> with large memory. May be worth reinvestigating
>
> Worth putting in the defconfig just for testing until then?

Absolutely!

>
>>
>> > * Add PPC_MEMTRACE - Small powernv debugfs driver for getting hardware traces.
>> > * Add MEMORY_FAILURE - Machine check exceptions can now drive memory failure.
>
>          ^^^^
> Okay for this one?

Yep definitely!

>
>> > * Turn on FANOTIFY - This is the current filesystem notification feature.
>> > * Turn on SCOM_DEBUGFS - Handy for hardware/firmware debugging, security risk?
>>
>> Yep, should not be in defconfig, IMHO
>
> Why not? Honest question, I hear some things about secure
> boot when I ask about this option but I'm not quite sure why, or
> what we are securing here.
>
> If the firmware does not want us to mess with scoms, it should
> restrict the call, no?
>

Yes, firmware definitely should. Do we need inband debugging?


>
>> > * Turn on async SCSI scanning - Let's see what breaks.
>> >
>> > * Make a bunch of USB hid drivers modules.
>> > * Make SCSI SG, SR, and FC modules - FC is huge.
>> > * Make video drivers (except AST GPU) modules - Also huge.
>> > * Add MLX5 driver as a module - Popular demand.
>> > * Make PCI serial driver a module - Uncommon?
>> >
>> > * Get rid of /dev/port - Not used.
>> > * Remove legacy BSD ttys - Long dead.
>> > * Remove IDE - Deprecated and replaced with ATA.
>> > * Remove WIRELESS - Until we get POWER9 laptops.
>> > * Remove RAW - Long deprecated in favour of direct IO.
>> > * Remove floppy, parport, and PS2 input devices - not supported.
>> > * Remove virtio drivers, ballooning - We're host only.
>>
>> I still think its good to have them, may be as modules? Should I
>> switch to powerpc64le_defconfig for a single config with everything --
>> same kernel as guest and bare metal?
>
> Well powernv_defconfig never supports PAPR guest. I think the ppc64
> defconfig does both (and pseries has no bare metal).
>
> Is there a reason to use them in host? And if yes, which ones? We
> could easily make them as modules.

I guess I should use powerpc64le_defconfig then

Balbir